Freshly cast or otherwise shaped glass articles are particularly sensitive to scratching which may be detrimental to the strength of the wall of the container.
To avoid this negative effect, it is customary to treat the surface of the freshly made glass article with a coating of a metal oxide, for example, which tends to inhibit scratching and, put otherwise, protectively coats the glass surface.
In general, the metal oxide has been applied to the glass containers while they are at temperatures above about 400.degree. C. having been formed immediately prior to the coating process and without reheating the glass articles. The metals which are used are tin and titanium since these have high affinity to the molecular structure of the glass and form oxides readily on the glass surfaces.
The coating with titanium oxides generally utilizes titanium in the form of its chloride and is carried out in a tunnel-like structure through which the glass containers pass and into which the titanium chloride reactant is introduced to decompose and form titanium oxide on the glass surface. The reaction takes place by contact of the titanium chloride with this surface and the titanium oxide precipitates readily thereon.
While there are various processes and devices for ensuring the contact of the reactant with the glass which have been considered to provide good effects, they have various disadvantages which complicate the production of the coated glass articles.
For example, there is a tendency toward condensation and there is some tendency to premature reaction of the reactant gases in the supply pipes of the apparatus, leading to deposits which partially or completely obstruct the flow passages.
Another problem arises in the form of a limitation in the coating efficiency in certain of the prior art techniques. In yet other cases, difficulties are encountered with the coating of the mouth of the glass vessel which complicate the application of metallic closures or create corrosion problems with such metallic closures or so modify the friction that such closures may tend to rotate when such rotation is not desirable.
In some cases, conventional apparatus has had to deal with problems resulting from the fact that the glass containers tend to fall transversely or to stack up and pack within the treatment chamber thereby requiring removal by hand and other expensive procedures.